(1) Field of the Invention
The present invention, the Flow Shield generally relates to an apparatus and method that reduces the amount of silt, sediment, and debris entering a storm sewer during water runoff from a construction site. The apparatus is a rigid structure covered with an exterior filter that fits over the opening of a standard combination curb and gutter system. The device is placed over the standard combination curb and gutter system during site construction to remove silt and sedimentation from water entering the sewer system. The Flow Shield can be quickly installed over a any standard curb or gutter inlet system. Removal of the Flow Shield can be performed quickly and easily upon the complete of construction site activities. The Flow Shield is stackable, allowing a number of devices to be stacked together to facilitate transport of the devices from job site to job site. Stackability also reduces the space required for storage of the Flow Shield. The Flow Shield does not retain moisture allowing it to be stored immediately after use. The filter attachment and design facilitates efficient silt and sedimentation filtering and removal of debris.
(2) Description of Related Art
Storm water runoff is produced when precipitation from rain and snow melt flows over land and impervious surfaces and does not percolate into the land. As the storm water runoff flows over land and impervious surfaces it accumulates silt, sediment, pollutants and other debris. The silt, sediment, pollutants and other debris can contaminate the water if the water is left untreated. Once the storm water runoff enters a storm sewer system, the silt, sedimentation, and debris can accumulate within the system obstructing the flow of runoff. Federal, state, and local authorities regulate runoff pollution and limit the amount of silt, sedimentation, and debris within storm water runoff. These regulations require commercial and residential construction to minimize particulate in runoff and to prevent the flow of particulate matter into a sewer system.
The types of storm sewer drain inlets in common use include curb inlets, gutter inlets, and combination curb and gutter inlets. A curb inlet is just a vertical opening in the curb. A gutter inlet includes an opening in a horizontal section of the road. Gutter inlets may also include a vertical section of drain stemming from the horizontal opening. Gutter inlets typically have a grate covering the opening, while curb inlets are typically open without a grate. Combination curb and gutter systems have a vertical curb opening and a horizontal grated opening in the bottom of the gutter.
During construction of both residential and commercial buildings, grading and land excavation are typically ongoing throughout the duration of construction activities. Construction equipment such as bull dozers, back hoes, and excavators are constantly tracking mud and debris onto newly built roads and existing streets. Rainfall can wash the mud and debris into nearby storm sewers that are designed to carry the water to nearby tributaries and to water treatment facilities. Although seeding and mulching is common practice during construction, erosion of exposed earth especially during heavy storms can be substantial. Heavy rainfall can strip a construction site of loose silt and sediment. The silt and sediment may drain into a nearby storm sewer system. And, over time, the silt and sediment can accumulate within the sewer system.
Environment regulations prevent the accumulation of silt and sediment in a sewer system. A builder found to be in violation of storm water runoff regulations can be sanctioned by federal, state, and local officials. If silt and sediment do accumulate in a sewer system, the process of removing the particulate can be time consuming and costly to the builder or developer. Often it is necessary to rent expensive equipment and to hire specialized personnel to physically enter the structure or pipe and remove the sedimentation. This can add cost to the construction project and be dangerous to the personnel removing the silt and sediment. Additionally, OSHA mandates relating to subjecting a worker to a confined work space may be violated subjecting the builder to additional sanctions.
A number of devices have been disclosed and implemented to reduce silt and sediment discharge into a storm sewer system. The simplest storm water filtration device is created by placing one or more bales of straw in front of or on top of a storm drain. “Wattles” are another simple device commonly seen on active construction sites to filter debris out of runoff before it enters a storm drain. A “wattle” is a tubular mesh bag made of jute, hemp, or another woven material that is typically filled with wood chips such as hog fuel, or with some other absorbent material such as straw. Wattles are also placed on top of or in front of a sewer grate. Bussey, Jr. et al (U.S. Pat. No. 7,744,308 B2) discloses a oval-shaped tubular mesh bag containing filter material that is placed in front of a drainage element to filter debris from the runoff. Each of these three devices is difficult or impossible to stake down and all of them are subject to floating away during a heavy downpour. These devices usually do a poor job of trapping silt and sediment.
McGinn (U.S. Pat. No. 7,131,787 B2) discloses a drain inlet cover to filter runoff entering a gutter inlet. The device includes a horizontal section lying on the road and a vertical section covering the opening in the curb. Each section includes a filter member lying between two apertured polymeric members. This device requires that a berm be placed around the horizontal section of the device so that some sediment can settle out of the sediment-bearing liquid before it reaches the device. The requirement that a berm be fashioned to remove sediment from storm water severely limits the utility of the device. Additionally, this device limits the size of the vertical filter member which permits the free flow of runoff into the space above the filter member and below the curb. This allows runoff to flow without any silt, sediment or debris removal, which may violate environmental laws and regulations subjecting the builder to penalty.
Moody (U.S. Pat. No. 8,051,568 B2) discloses a temporary grate cover installed during construction activities. The device is composed of an expanded metal such as stainless steel with an attached geotextile fabric. The fabric is a filter weave high flow monofilament fabric, such as a woven polyethylene fabric. The device is attached to the grate with toggle bolts. This grate cover includes a flattened expanded metal with diamond shaped openings, which may be sized at about ¾×1¾″. Because curb inlets lack a grate in which to attach this device, this device can only be used on gutter inlet systems. The Moody device includes an embodiment for use with systems including a curb opening. This embodiment has one side turned up to form a vertical filter portion. But this embodiment offers no mechanism to attach the turned up portion of the device to the curb inlet, which weakens the device making less effective in heavy downpours or when heavy or a large quantity of debris is present in the runoff.
D'Andreta et al. (U.S. Pat. No. 7,901,160 B2) discloses a gutter grate cover molded onto a storm drain by driving over it or otherwise deflecting it from a generally upright orientation. The device is self-supporting and includes two substantially solid sheet portions containing apertures. A filter is positioned so that it filters runoff entering through the apertures. This device is molded to the curb by driving a bobcat or other wheeled vehicle over the device. But, concrete curbs are easily damaged by contact with construction equipment. The use of this device at a construction site may necessitate the use of remedial measures to remove and replace damaged curbs.